/**
 * Copyright (c) 2008, Nathan Sweet
 * All rights reserved.
 * <p>
 * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
 * <p>
 * 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
 * 3. Neither the name of Esoteric Software nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
 * <p>
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package io.effi.rpc.support.reflect;

import io.effi.rpc.common.util.ReflectionUtil;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Type;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.ArrayList;

import static org.objectweb.asm.Opcodes.*;

/**
 * Field Access.
 */
public abstract class FieldAccess {
    private String[] fieldNames;

    private Class<?>[] fieldTypes;

    private Field[] fields;

    /**
     * @param type Must not be the Object class, an interface, a primitive type, or void.
     */
    public static FieldAccess get(Class<?> type) {
        if (type.getSuperclass() == null)
            throw new IllegalArgumentException("The type must not be the Object class, an interface, a primitive type, or void.");

        ArrayList<Field> fields = new ArrayList<>();
        Class<?> nextClass = type;
        while (nextClass != Object.class) {
            Field[] declaredFields = nextClass.getDeclaredFields();
            for (Field field : declaredFields) {
                int modifiers = field.getModifiers();
                if (Modifier.isStatic(modifiers)) continue;
                if (Modifier.isPrivate(modifiers)) continue;
                fields.add(field);
            }
            nextClass = nextClass.getSuperclass();
        }

        String[] fieldNames = new String[fields.size()];
        Class<?>[] fieldTypes = new Class<?>[fields.size()];
        for (int i = 0, n = fieldNames.length; i < n; i++) {
            fieldNames[i] = fields.get(i).getName();
            fieldTypes[i] = fields.get(i).getType();
        }

        String className = type.getName();
        String accessClassName = className + "FieldAccess";
        if (accessClassName.startsWith("java.")) accessClassName = "reflectasm." + accessClassName;

        Class<?> accessClass;
        AccessClassLoader loader = AccessClassLoader.get(type);
        synchronized (loader) {
            accessClass = loader.loadAccessClass(accessClassName);
            if (accessClass == null) {
                String accessClassNameInternal = accessClassName.replace('.', '/');
                String classNameInternal = className.replace('.', '/');

                ClassWriter cw = new ClassWriter(0);
                cw.visit(V1_6, ACC_PUBLIC + ACC_SUPER + ACC_SYNTHETIC, accessClassNameInternal, null, "io/effi/rpc/protocol/support/reflect/FieldAccess",
                        null);
                insertConstructor(cw);
                insertGetObject(cw, classNameInternal, fields);
                insertSetObject(cw, classNameInternal, fields);
                insertGetPrimitive(cw, classNameInternal, fields, Type.BOOLEAN_TYPE);
                insertSetPrimitive(cw, classNameInternal, fields, Type.BOOLEAN_TYPE);
                insertGetPrimitive(cw, classNameInternal, fields, Type.BYTE_TYPE);
                insertSetPrimitive(cw, classNameInternal, fields, Type.BYTE_TYPE);
                insertGetPrimitive(cw, classNameInternal, fields, Type.SHORT_TYPE);
                insertSetPrimitive(cw, classNameInternal, fields, Type.SHORT_TYPE);
                insertGetPrimitive(cw, classNameInternal, fields, Type.INT_TYPE);
                insertSetPrimitive(cw, classNameInternal, fields, Type.INT_TYPE);
                insertGetPrimitive(cw, classNameInternal, fields, Type.LONG_TYPE);
                insertSetPrimitive(cw, classNameInternal, fields, Type.LONG_TYPE);
                insertGetPrimitive(cw, classNameInternal, fields, Type.DOUBLE_TYPE);
                insertSetPrimitive(cw, classNameInternal, fields, Type.DOUBLE_TYPE);
                insertGetPrimitive(cw, classNameInternal, fields, Type.FLOAT_TYPE);
                insertSetPrimitive(cw, classNameInternal, fields, Type.FLOAT_TYPE);
                insertGetPrimitive(cw, classNameInternal, fields, Type.CHAR_TYPE);
                insertSetPrimitive(cw, classNameInternal, fields, Type.CHAR_TYPE);
                insertGetString(cw, classNameInternal, fields);
                cw.visitEnd();
                accessClass = loader.defineAccessClass(accessClassName, cw.toByteArray());
            }
        }
        try {
            FieldAccess access = (FieldAccess) ReflectionUtil.newInstance(accessClass);
            access.fieldNames = fieldNames;
            access.fieldTypes = fieldTypes;
            access.fields = fields.toArray(Field[]::new);
            return access;
        } catch (Throwable t) {
            throw new RuntimeException("Error constructing field access class: " + accessClassName, t);
        }
    }

    private static void insertConstructor(ClassWriter cw) {
        MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
        mv.visitCode();
        mv.visitVarInsn(ALOAD, 0);
        mv.visitMethodInsn(INVOKESPECIAL, "io/effi/rpc/protocol/support/reflect/FieldAccess", "<init>", "()V", false);
        mv.visitInsn(RETURN);
        mv.visitMaxs(1, 1);
        mv.visitEnd();
    }

    private static void insertSetObject(ClassWriter cw, String classNameInternal, ArrayList<Field> fields) {
        int maxStack = 6;
        MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, "set", "(Ljava/lang/Object;ILjava/lang/Object;)V", null, null);
        mv.visitCode();
        mv.visitVarInsn(ILOAD, 2);

        if (!fields.isEmpty()) {
            maxStack--;
            Label[] labels = new Label[fields.size()];
            for (int i = 0, n = labels.length; i < n; i++)
                labels[i] = new Label();
            Label defaultLabel = new Label();
            mv.visitTableSwitchInsn(0, labels.length - 1, defaultLabel, labels);

            for (int i = 0, n = labels.length; i < n; i++) {
                Field field = fields.get(i);
                Type fieldType = Type.getType(field.getType());

                mv.visitLabel(labels[i]);
                mv.visitFrame(F_SAME, 0, null, 0, null);
                mv.visitVarInsn(ALOAD, 1);
                mv.visitTypeInsn(CHECKCAST, classNameInternal);
                mv.visitVarInsn(ALOAD, 3);

                switch (fieldType.getSort()) {
                    case Type.BOOLEAN:
                        mv.visitTypeInsn(CHECKCAST, "java/lang/Boolean");
                        mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Boolean", "booleanValue", "()Z", false);
                        break;
                    case Type.BYTE:
                        mv.visitTypeInsn(CHECKCAST, "java/lang/Byte");
                        mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Byte", "byteValue", "()B", false);
                        break;
                    case Type.CHAR:
                        mv.visitTypeInsn(CHECKCAST, "java/lang/Character");
                        mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Character", "charValue", "()C", false);
                        break;
                    case Type.SHORT:
                        mv.visitTypeInsn(CHECKCAST, "java/lang/Short");
                        mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Short", "shortValue", "()S", false);
                        break;
                    case Type.INT:
                        mv.visitTypeInsn(CHECKCAST, "java/lang/Integer");
                        mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Integer", "intValue", "()I", false);
                        break;
                    case Type.FLOAT:
                        mv.visitTypeInsn(CHECKCAST, "java/lang/Float");
                        mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Float", "floatValue", "()F", false);
                        break;
                    case Type.LONG:
                        mv.visitTypeInsn(CHECKCAST, "java/lang/Long");
                        mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Long", "longValue", "()J", false);
                        break;
                    case Type.DOUBLE:
                        mv.visitTypeInsn(CHECKCAST, "java/lang/Double");
                        mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Double", "doubleValue", "()D", false);
                        break;
                    case Type.ARRAY:
                        mv.visitTypeInsn(CHECKCAST, fieldType.getDescriptor());
                        break;
                    case Type.OBJECT:
                        mv.visitTypeInsn(CHECKCAST, fieldType.getInternalName());
                        break;
                }

                mv.visitFieldInsn(PUTFIELD, field.getDeclaringClass().getName().replace('.', '/'), field.getName(),
                        fieldType.getDescriptor());
                mv.visitInsn(RETURN);
            }

            mv.visitLabel(defaultLabel);
            mv.visitFrame(F_SAME, 0, null, 0, null);
        }
        insertThrowExceptionForFieldNotFound(mv);
        mv.visitMaxs(maxStack, 4);
        mv.visitEnd();
    }

    private static void insertGetObject(ClassWriter cw, String classNameInternal, ArrayList<Field> fields) {
        int maxStack = 6;
        MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, "get", "(Ljava/lang/Object;I)Ljava/lang/Object;", null, null);
        mv.visitCode();
        mv.visitVarInsn(ILOAD, 2);

        if (!fields.isEmpty()) {
            maxStack--;
            Label[] labels = new Label[fields.size()];
            for (int i = 0, n = labels.length; i < n; i++)
                labels[i] = new Label();
            Label defaultLabel = new Label();
            mv.visitTableSwitchInsn(0, labels.length - 1, defaultLabel, labels);

            for (int i = 0, n = labels.length; i < n; i++) {
                Field field = fields.get(i);

                mv.visitLabel(labels[i]);
                mv.visitFrame(F_SAME, 0, null, 0, null);
                mv.visitVarInsn(ALOAD, 1);
                mv.visitTypeInsn(CHECKCAST, classNameInternal);
                mv.visitFieldInsn(GETFIELD, field.getDeclaringClass().getName().replace('.', '/'), field.getName(),
                        Type.getDescriptor(field.getType()));

                Type fieldType = Type.getType(field.getType());
                switch (fieldType.getSort()) {
                    case Type.BOOLEAN:
                        mv.visitMethodInsn(INVOKESTATIC, "java/lang/Boolean", "valueOf", "(Z)Ljava/lang/Boolean;", false);
                        break;
                    case Type.BYTE:
                        mv.visitMethodInsn(INVOKESTATIC, "java/lang/Byte", "valueOf", "(B)Ljava/lang/Byte;", false);
                        break;
                    case Type.CHAR:
                        mv.visitMethodInsn(INVOKESTATIC, "java/lang/Character", "valueOf", "(C)Ljava/lang/Character;", false);
                        break;
                    case Type.SHORT:
                        mv.visitMethodInsn(INVOKESTATIC, "java/lang/Short", "valueOf", "(S)Ljava/lang/Short;", false);
                        break;
                    case Type.INT:
                        mv.visitMethodInsn(INVOKESTATIC, "java/lang/Integer", "valueOf", "(I)Ljava/lang/Integer;", false);
                        break;
                    case Type.FLOAT:
                        mv.visitMethodInsn(INVOKESTATIC, "java/lang/Float", "valueOf", "(F)Ljava/lang/Float;", false);
                        break;
                    case Type.LONG:
                        mv.visitMethodInsn(INVOKESTATIC, "java/lang/Long", "valueOf", "(J)Ljava/lang/Long;", false);
                        break;
                    case Type.DOUBLE:
                        mv.visitMethodInsn(INVOKESTATIC, "java/lang/Double", "valueOf", "(D)Ljava/lang/Double;", false);
                        break;
                }

                mv.visitInsn(ARETURN);
            }

            mv.visitLabel(defaultLabel);
            mv.visitFrame(F_SAME, 0, null, 0, null);
        }
        insertThrowExceptionForFieldNotFound(mv);
        mv.visitMaxs(maxStack, 3);
        mv.visitEnd();
    }

    private static void insertGetString(ClassWriter cw, String classNameInternal, ArrayList<Field> fields) {
        int maxStack = 6;
        MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, "getString", "(Ljava/lang/Object;I)Ljava/lang/String;", null, null);
        mv.visitCode();
        mv.visitVarInsn(ILOAD, 2);

        if (!fields.isEmpty()) {
            maxStack--;
            Label[] labels = new Label[fields.size()];
            Label labelForInvalidTypes = new Label();
            boolean hasAnyBadTypeLabel = false;
            for (int i = 0, n = labels.length; i < n; i++) {
                if (fields.get(i).getType().equals(String.class))
                    labels[i] = new Label();
                else {
                    labels[i] = labelForInvalidTypes;
                    hasAnyBadTypeLabel = true;
                }
            }
            Label defaultLabel = new Label();
            mv.visitTableSwitchInsn(0, labels.length - 1, defaultLabel, labels);

            for (int i = 0, n = labels.length; i < n; i++) {
                if (!labels[i].equals(labelForInvalidTypes)) {
                    Field field = fields.get(i);
                    mv.visitLabel(labels[i]);
                    mv.visitFrame(F_SAME, 0, null, 0, null);
                    mv.visitVarInsn(ALOAD, 1);
                    mv.visitTypeInsn(CHECKCAST, classNameInternal);
                    mv.visitFieldInsn(GETFIELD, field.getDeclaringClass().getName().replace('.', '/'), field.getName(),
                            "Ljava/lang/String;");
                    mv.visitInsn(ARETURN);
                }
            }
            // Rest of fields: different type
            if (hasAnyBadTypeLabel) {
                mv.visitLabel(labelForInvalidTypes);
                mv.visitFrame(F_SAME, 0, null, 0, null);
                insertThrowExceptionForFieldType(mv, "String");
            }
            // Default: field not found
            mv.visitLabel(defaultLabel);
            mv.visitFrame(F_SAME, 0, null, 0, null);
        }
        insertThrowExceptionForFieldNotFound(mv);
        mv.visitMaxs(maxStack, 3);
        mv.visitEnd();
    }

    private static void insertSetPrimitive(ClassWriter cw, String classNameInternal, ArrayList<Field> fields,
                                           Type primitiveType) {
        int maxStack = 6;
        int maxLocals = 4; // See correction below for LLOAD and DLOAD
        final String setterMethodName;
        final String typeNameInternal = primitiveType.getDescriptor();
        final int loadValueInstruction;
        switch (primitiveType.getSort()) {
            case Type.BOOLEAN:
                setterMethodName = "setBoolean";
                loadValueInstruction = ILOAD;
                break;
            case Type.BYTE:
                setterMethodName = "setByte";
                loadValueInstruction = ILOAD;
                break;
            case Type.CHAR:
                setterMethodName = "setChar";
                loadValueInstruction = ILOAD;
                break;
            case Type.SHORT:
                setterMethodName = "setShort";
                loadValueInstruction = ILOAD;
                break;
            case Type.INT:
                setterMethodName = "setInt";
                loadValueInstruction = ILOAD;
                break;
            case Type.FLOAT:
                setterMethodName = "setFloat";
                loadValueInstruction = FLOAD;
                break;
            case Type.LONG:
                setterMethodName = "setLong";
                loadValueInstruction = LLOAD;
                maxLocals++; // (LLOAD and DLOAD actually load two slots)
                break;
            case Type.DOUBLE:
                setterMethodName = "setDouble";
                loadValueInstruction = DLOAD;
                maxLocals++; // (LLOAD and DLOAD actually load two slots)
                break;
            default:
                setterMethodName = "set";
                loadValueInstruction = ALOAD;
                break;
        }
        MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, setterMethodName, "(Ljava/lang/Object;I" + typeNameInternal + ")V", null,
                null);
        mv.visitCode();
        mv.visitVarInsn(ILOAD, 2);

        if (!fields.isEmpty()) {
            maxStack--;
            Label[] labels = new Label[fields.size()];
            Label labelForInvalidTypes = new Label();
            boolean hasAnyBadTypeLabel = false;
            for (int i = 0, n = labels.length; i < n; i++) {
                if (Type.getType(fields.get(i).getType()).equals(primitiveType))
                    labels[i] = new Label();
                else {
                    labels[i] = labelForInvalidTypes;
                    hasAnyBadTypeLabel = true;
                }
            }
            Label defaultLabel = new Label();
            mv.visitTableSwitchInsn(0, labels.length - 1, defaultLabel, labels);

            for (int i = 0, n = labels.length; i < n; i++) {
                if (!labels[i].equals(labelForInvalidTypes)) {
                    Field field = fields.get(i);
                    mv.visitLabel(labels[i]);
                    mv.visitFrame(F_SAME, 0, null, 0, null);
                    mv.visitVarInsn(ALOAD, 1);
                    mv.visitTypeInsn(CHECKCAST, classNameInternal);
                    mv.visitVarInsn(loadValueInstruction, 3);
                    mv.visitFieldInsn(PUTFIELD, field.getDeclaringClass().getName().replace('.', '/'), field.getName(),
                            typeNameInternal);
                    mv.visitInsn(RETURN);
                }
            }
            // Rest of fields: different type
            if (hasAnyBadTypeLabel) {
                mv.visitLabel(labelForInvalidTypes);
                mv.visitFrame(F_SAME, 0, null, 0, null);
                insertThrowExceptionForFieldType(mv, primitiveType.getClassName());
            }
            // Default: field not found
            mv.visitLabel(defaultLabel);
            mv.visitFrame(F_SAME, 0, null, 0, null);
        }
        mv = insertThrowExceptionForFieldNotFound(mv);
        mv.visitMaxs(maxStack, maxLocals);
        mv.visitEnd();
    }

    private static void insertGetPrimitive(ClassWriter cw, String classNameInternal, ArrayList<Field> fields,
                                           Type primitiveType) {
        int maxStack = 6;
        final String getterMethodName;
        final String typeNameInternal = primitiveType.getDescriptor();
        final int returnValueInstruction = switch (primitiveType.getSort()) {
            case Type.BOOLEAN -> {
                getterMethodName = "getBoolean";
                yield IRETURN;
            }
            case Type.BYTE -> {
                getterMethodName = "getByte";
                yield IRETURN;
            }
            case Type.CHAR -> {
                getterMethodName = "getChar";
                yield IRETURN;
            }
            case Type.SHORT -> {
                getterMethodName = "getShort";
                yield IRETURN;
            }
            case Type.INT -> {
                getterMethodName = "getInt";
                yield IRETURN;
            }
            case Type.FLOAT -> {
                getterMethodName = "getFloat";
                yield FRETURN;
            }
            case Type.LONG -> {
                getterMethodName = "getLong";
                yield LRETURN;
            }
            case Type.DOUBLE -> {
                getterMethodName = "getDouble";
                yield DRETURN;
            }
            default -> {
                getterMethodName = "get";
                yield ARETURN;
            }
        };
        MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, getterMethodName, "(Ljava/lang/Object;I)" + typeNameInternal, null, null);
        mv.visitCode();
        mv.visitVarInsn(ILOAD, 2);

        if (!fields.isEmpty()) {
            maxStack--;
            Label[] labels = new Label[fields.size()];
            Label labelForInvalidTypes = new Label();
            boolean hasAnyBadTypeLabel = false;
            for (int i = 0, n = labels.length; i < n; i++) {
                if (Type.getType(fields.get(i).getType()).equals(primitiveType))
                    labels[i] = new Label();
                else {
                    labels[i] = labelForInvalidTypes;
                    hasAnyBadTypeLabel = true;
                }
            }
            Label defaultLabel = new Label();
            mv.visitTableSwitchInsn(0, labels.length - 1, defaultLabel, labels);

            for (int i = 0, n = labels.length; i < n; i++) {
                Field field = fields.get(i);
                if (!labels[i].equals(labelForInvalidTypes)) {
                    mv.visitLabel(labels[i]);
                    mv.visitFrame(F_SAME, 0, null, 0, null);
                    mv.visitVarInsn(ALOAD, 1);
                    mv.visitTypeInsn(CHECKCAST, classNameInternal);
                    mv.visitFieldInsn(GETFIELD, field.getDeclaringClass().getName().replace('.', '/'), field.getName(),
                            typeNameInternal);
                    mv.visitInsn(returnValueInstruction);
                }
            }
            // Rest of fields: different type
            if (hasAnyBadTypeLabel) {
                mv.visitLabel(labelForInvalidTypes);
                mv.visitFrame(F_SAME, 0, null, 0, null);
                insertThrowExceptionForFieldType(mv, primitiveType.getClassName());
            }
            // Default: field not found
            mv.visitLabel(defaultLabel);
            mv.visitFrame(F_SAME, 0, null, 0, null);
        }
        insertThrowExceptionForFieldNotFound(mv);
        mv.visitMaxs(maxStack, 3);
        mv.visitEnd();
    }

    private static MethodVisitor insertThrowExceptionForFieldNotFound(MethodVisitor mv) {
        mv.visitTypeInsn(NEW, "java/lang/IllegalArgumentException");
        mv.visitInsn(DUP);
        mv.visitTypeInsn(NEW, "java/lang/StringBuilder");
        mv.visitInsn(DUP);
        mv.visitLdcInsn("Field not found: ");
        mv.visitMethodInsn(INVOKESPECIAL, "java/lang/StringBuilder", "<init>", "(Ljava/lang/String;)V", false);
        mv.visitVarInsn(ILOAD, 2);
        mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append", "(I)Ljava/lang/StringBuilder;", false);
        mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "toString", "()Ljava/lang/String;", false);
        mv.visitMethodInsn(INVOKESPECIAL, "java/lang/IllegalArgumentException", "<init>", "(Ljava/lang/String;)V", false);
        mv.visitInsn(ATHROW);
        return mv;
    }

    private static void insertThrowExceptionForFieldType(MethodVisitor mv, String fieldType) {
        mv.visitTypeInsn(NEW, "java/lang/IllegalArgumentException");
        mv.visitInsn(DUP);
        mv.visitTypeInsn(NEW, "java/lang/StringBuilder");
        mv.visitInsn(DUP);
        mv.visitLdcInsn("Field not declared as " + fieldType + ": ");
        mv.visitMethodInsn(INVOKESPECIAL, "java/lang/StringBuilder", "<init>", "(Ljava/lang/String;)V", false);
        mv.visitVarInsn(ILOAD, 2);
        mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append", "(I)Ljava/lang/StringBuilder;", false);
        mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "toString", "()Ljava/lang/String;", false);
        mv.visitMethodInsn(INVOKESPECIAL, "java/lang/IllegalArgumentException", "<init>", "(Ljava/lang/String;)V", false);
        mv.visitInsn(ATHROW);
    }

    public int getIndex(String fieldName) {
        for (int i = 0, n = fieldNames.length; i < n; i++)
            if (fieldNames[i].equals(fieldName)) return i;
        throw new IllegalArgumentException("Unable to find non-private field: " + fieldName);
    }

    public int getIndex(Field field) {
        for (int i = 0, n = fields.length; i < n; i++)
            if (fields[i].equals(field)) return i;
        throw new IllegalArgumentException("Unable to find non-private field: " + field);
    }

    public void set(Object instance, String fieldName, Object value) {
        set(instance, getIndex(fieldName), value);
    }

    public Object get(Object instance, String fieldName) {
        return get(instance, getIndex(fieldName));
    }

    public int getFieldCount() {
        return fieldTypes.length;
    }

    public void setFields(Field[] fields) {
        this.fields = fields;
    }

    public abstract void set(Object instance, int fieldIndex, Object value);

    public abstract void setBoolean(Object instance, int fieldIndex, boolean value);

    public abstract void setByte(Object instance, int fieldIndex, byte value);

    public abstract void setShort(Object instance, int fieldIndex, short value);

    public abstract void setInt(Object instance, int fieldIndex, int value);

    public abstract void setLong(Object instance, int fieldIndex, long value);

    public abstract void setDouble(Object instance, int fieldIndex, double value);

    public abstract void setFloat(Object instance, int fieldIndex, float value);

    public abstract void setChar(Object instance, int fieldIndex, char value);

    public abstract Object get(Object instance, int fieldIndex);

    public abstract String getString(Object instance, int fieldIndex);

    public abstract char getChar(Object instance, int fieldIndex);

    public abstract boolean getBoolean(Object instance, int fieldIndex);

    public abstract byte getByte(Object instance, int fieldIndex);

    public abstract short getShort(Object instance, int fieldIndex);

    public abstract int getInt(Object instance, int fieldIndex);

    public abstract long getLong(Object instance, int fieldIndex);

    public abstract double getDouble(Object instance, int fieldIndex);

    public abstract float getFloat(Object instance, int fieldIndex);

}